The present invention relates generally to laminated label sheets, and, more specifically, to the manufacture thereof.
Label sheets are commonly available in various configurations with and without printing thereon. A typical label sheet is a laminate of a paper overlay and an underlying release liner. An adhesive bonds the overlay to the liner in the finished article.
In typical use, information is printed atop the overlay, and the overlay is then removed from the liner by being peeled therefrom. The peeled away label has exposed adhesive so that it may be pressed against paper or other object for attachment thereto. A typical release liner is coated over one side with liquid silicone which is thermally cured for providing a low adhesion surface thereatop to which the overlay is temporarily bonded. The adhesive provides a weak bond between the overlay and the silicone liner which sufficiently maintains together the laminate until it is desired to remove the overlay from the liner.
More complex label sheets include several labels or decals in the overlay defined by respective perimeter die-cuts therebetween which allow removal of individual labels from the liner. The individual labels may be directly adjacent to each other or there may be an intervening label rim or border which remains attached to the liner after the individual labels are peeled away.
A further increase in complexity of the label sheet includes an integral paper form attached to the label portion of the overlay which does not overlie the liner. This type of label sheet may be manufactured using a lap joining method wherein the label and liner laminate is premanufactured and lap joined along an edge thereof to the paper form. In another, integrated, method of manufacture, the entire overlay, including the label and form portions thereof, is separately manufactured in a common sheet and the liner is then bonded below the label portion thereof.
These various label sheets nevertheless use a commonly fabricated release liner which is typically manufactured in large rolls with the silicone in liquid form being applied over the entire surface of the liner paper which is then thermally cured. The large roll of release liner is then cut into individual smaller rolls for use in various label sheet applications as required.
Since the low adhesion silicone covers the entire front surface of the release liner, only weak adhesive bonds with the paper overlay may be formed therewith. This presents a problem when several individual labels are formed in the overlay. For example, when the label sheet is passed through a laser printer, individual labels may separate from the liner as the adhesive is softened under heat and the sheet is bent tightly around narrow rollers. Not only may the label sheet be damaged during laser printing, but the released portions thereof have exposed adhesive which may adhere the overlay to internal components of the printer causing jamming thereof. Additional adhesive may also be squeezed out from between the labels and liner due to the heat and squeezing in the printer, and may also lead to printer jamming.
Furthermore, when an individual label is removed from an adjoining label border, the border portion itself may also separate from the liner, and the exposed adhesive on the border may inadvertently attach the border to other papers which is undesirable.
Another problem attributable to this liner construction occurs when the overlay includes a perforation line. Such lines are provided to tear apart portions of the label for various reasons. Since the label necessarily has a weak bond with the liner, tearing the label along the perforations typically breaks this bond and allows the label to slide on the liner and typically experience side tears emanating from the perforation line.
Since the liner is typically manufactured in large rolls, cut to size, and used for various applications, it is not practical or even possible to provide printing atop the liner and below the silicone surface. This leaves only the front and back sides of the overlay and the back side of the liner as available surfaces for printing, and therefore decreases the potential efficiency of the label sheet.
Accordingly, it is desired to provide an improved label sheet which resolves one or more of these various limitations in conventionally manufactured label sheets.